1. Field of the Invention
The present invention relates to an image recording apparatus configured to perform image recording by reciprocating a recording head in main scanning directions together with a carriage, and in particular to such an image recording apparatus in which a power of a drive motor is selectively transmitted to a plurality of drive portions.
2. Description of the Related Art
An ink-jet printer is known as an image recording apparatus configured to record an image on a recording medium by ejecting ink based on input signals.
The ink jetprinter performs image recording by selectively ejecting ink from the recording head to the recording medium during conveyance of the recording sheet from a supply tray to an output tray. The recording sheet is supplied from the supply tray and is conveyed in a conveyance path utilizing rollers such as a supply roller and conveying rollers. Specifically, when the recording sheet is supplied and conveyed, the rollers are rotated while being held in pressing contact with the recording sheet. As a drive source for the rollers, a motor such as a DC motor or a stepping motor is used. A drive power is transmitted from the motor to the rollers by a drive-power transmitting mechanism including pinion gears, a timing belt, and so on.
The recording head of the ink jetprinter may suffer from ejection failure of ink due to air bubbles generated in nozzles from which the ink is ejected and clogging of foreign matters in the nozzles. For prevention of and recovery from the ejection failure of the ink, there is known a technique of removing, by suction, the air bubbles and the foreign matters from the nozzles of the recording head. Such a technique is called purging. A maintenance unit for performing the purging includes a cap for covering the nozzles of the recording head and a pump for reducing a pressure in the cap. The motor is used as a drive source for driving the pump of the maintenance unit and for driving a cam for switching an operating state of an air discharging valve of the maintenance unit. The drive power is transmitted from the motor to the drive portions by the drive-power transmitting mechanism described above.
There have been known image recording apparatus equipped with a switching mechanism for switching the drive portions to which the drive power of the motor as the drive source is to be transmitted. The switching mechanism selectively transmits the drive power to the drive portions depending upon a position of the carriage. Thus, the drive power is transmitted from a single drive source to the conveying rollers when image recording is performed and to the maintenance unit when the purging is performed, for instance.